2-subsituted tetrahydropyran and 2-substituted tetrahydrofuran-2-peroxy compounds

ABSTRACT

ETHER PEROXIDES OF THE FORMULA   R7-CH2-C(-R8)(-O-R3)-O-O-R10   HAVING LOW THERMAL STABILITY DUE TO THE PRESENCE OF AN ALKOXY GROUP (R3O-) ON THE SAME CARBON ATOM TO WHICH THE PEROXY (-OO-) GROUP IS ATTACHED, SUCH AS BRIS-2&#39;&#39;,2&#39;&#39;(2-METHYL-TETRAHYDROFURYL) PEROXIDE, WHICH ARE USEFUL AS POLYMERIZATION INITIATORS.

Patented May 14, 1974 United States Patent Oflice Int. Cl. C07d 5/04,7/0

U.S. Cl. 260-6453 7 Claims ABSTRACT OF THE DISCLOSURE Ether peroxides ofthe formula having low thermal stability due to the presence of analkoxy group (R 0--) on the same carbon atom to which the peroxy (-OO--)group is attached, such as bis-2,2- (2-methyl-tetrahydrofuryl) peroxide,which are useful as polymerization initiators.

This application is a division of copending application Ser. No.585,295, filed Oct. 10, 1966, now U.S. Pat. 3,576,826, dated Apr. 27,1971.

This invention relates to a novel process for the preparation of etherperoxides and hydroperoxides having an ether oxygen and a peroxy oxygenattached to a common carbon atom. Also the invention relates to novelether peroxides and hydroperoxides of this type.

Herein peroxy or dioxy" refers to the OO- group and hydroperoxy refersspecifically to the --OO-H group.

In all instances herein the numerical subscript following R, such as Ris being used as an identification tag only and is not intended toindicate the presence of more than one of said Rs.

A need exists for radical initiators operable in the peroxyestertemperature range but which do not contain carbonyl groups. Carbonylresidues on polymer chains have been considered to be the cause of poorlight and oxidative stability in several commercial polymers.

Several resin manufacturers have expressed an interest in thepossibility of using a dialkyl peroxide that would have a half-life nearthat of t-butyl perbenzoate. Three dialkyl peroxides were prepared; theywere too thermally stable to be replacements for peroxyesters.

The diperoxyketals have half-lives in the peroxyester range but arereported to be very shock sensitive. The preparation of peroxyketals waspatented by Shell in 1946 but the compounds were never oflered on acommercial scale presumably because of their hazardous nature.

A principal object of this invention is to provide peroxides which havesubstantially the effectiveness of com mercial peroxyesters, e.g.,t-butyl perbenzoate.

Ropp in U.S. Pat. No. 2,776,319, Ian. 1, 1957 discloses a process forpreparing ether peroxides by reacting a non substituted vinyl ether andan organic hydroperoxide, using an acid catalyst. When the Ropp processis applied to an a-substituted vinyl ether the corresponding etherperoxide is obtained in very low yield as a part of a mixture ofreaction products. This and other problems are illustrated later onherein.

Another principal object is a process for producing substituted etherperoxides in high yield and/or less byproduct formation.

Instead of the ether proxides having the substituent," the ether oxygenand a peroxy oxygen all on a common carbon atom, it is desirable to havethe peroxy oxygen part of a hydroperoxy group. Such ether hydroperoxidescannot be obtained by the Ropp method.

Still another principal object is a process for producing substitutedether hydroperoxides.

Other objects will be apparent in the course of the detailed descriptionof the invention.

A novel process for making ether peroxides or hydroperoxides has beendiscovered. Broadly the process involves the direct reaction, in theabsence of a catalyst, of

(III) to produce the corresponding substituted ether peroxide:

where:

(1) su is an organic radical;

(2) R is an aliphatic, cycloaliphatic or aromatic radical;

(3) R and R are H, aliphatic, cycloaliphatic or aromatic radicals;

(4) R is H, aliphatic or cycloaliphatic radical;

(5) p is an integer equal to at least 1, usually 1-3;

(6) R O-, C and sub together may form a ring; and

(7) sub, C, and -CHR R together form a ring when sub, C and CR6R1together form a ring.

Also there has been discovered a novel class of ether peroxides andhydroperoxides having the formula:

(IV) R1 Rs- H R: 0-4) 0 O R;

where: (a) R is H, aliphatic, cycloaliphatic,

(b) R, and R are aliphatic, cycloaliphatic or aromatic; (c) R isaliphatic or cycloaliphatic; (d) R and R are H, aliphatic,cycloaliphatic, or aromatic; (e) C, R6R7HC- and --OR together may form aring; (f) C, R R HC- and -R,Y together mal form a ring; and Y is Furtherthere has been discovered another novel class of ether peroxides havingthe formula:

RIC-H R30-- I -00Rm R4X 3 where: (i) R and R are aliphatic,cycloaliphatic or aromatic; (ii) R and R are H, aliphatic,cycloaliphatic, or aromatic; (iii) X is (iv) R is aliphatic orcycloaliphatic; (V) R is (vi) C, OR and R H HC- together may form aring; and ('vii) C, R X and R6R'1HC' together may form a ring.

THE PROCESS OF THE INVENTION ess; also hydrogen peroxide itself may beused as well as the organohydroperoxide.

Although the various Rs present in vinyl ether I and hydroperoxide IIcan be substituted with non-hydrocarbon groups or radicals, morecommonly these are hydrocarbon radicals.

Sub can be an organic radical; self-evidently, sub should not containgroups, etcrwhich would interfere with the reaction. (This is also trueof the various Rs.) More commonly, sub is a hydrocarbon radical, ahalohydrocarbon radical, or a hydrocarbon radical substituted with anester group, or ether group, or peroxyester group or amide group. Themore commercial hydroperoxides are most likely to be used as R (OOH)Illustrative of these are the alkyl hydroperoxides and dihydroperoxideshaving up to 18 carbon atoms; the cycloalkyl hydroperoxides such ascyclohexyl hydroperoxide and Decalin hydroperoxide; olefin hydroperoxideespecially the alkynyl such as dimethyl propynyl hydro-hydropcroxide,and di(peroxyisopropyl) benzene.

The reaction proceeds smoothly at temperatures below the decompositiontemperature of the least stable reactant or product. Usually thereaction temperature is held below about 60 C. Reaction rates areconvenient in range of about 0 C.50 C. Ambient temperatures of about 15C. are convenient for most reaction systems.

The reaction is carried out in the liquid state in a nonaqueous medium,which may be provided by the reactants themselves, and the reaction mayhave to the carried out at elevated pressure.

Any inert liquid organic solvent for the particular reactants may beused. Illustrative are ethers; benzene hydrocarbons, such as benzene andtoluene; saturated hydrocarbons such a petroleum ether, hexane,cyclohexane; halohydrocarbons.

The relative proportions of the reactants charged to the reaction zonemay cover a broad range dependent on the particular reactants. In somecases an excess of one reactant over the other is desirable. However, itis been observed that charging about the stoichiometric proportion ofreactants gives desirably good yields with a minimum of undesired sidereaction products.

It is been found that particularly in small size batch reactions it iseasier to control the temperature of the contents of the reactorcharging all of one reactant, and solvent if any is being used, into thereactor; then the other reactant is added incrementally to the reactorat a rate such that the temperature is maintained at about the desiredpoint. ffIncrementallyf includes addition of discrete quantities atregular intervals and also continuous addition at a controlled rate.

It is also possible, and probably preferable in a larger scale, tocontinuously intermingle two streams of reactants in. a reaction systempermitting close temperature control of the mixed stream. It is to beunderstood that the intermingling of the reactants is not limited to theabovedescribed illustrative procedures.

Thereaction rate and temperature control are facilitated by-maintainingthe contents of the reaction zone in an agitated condition both duringthe addition of the reactant'or reactants and for a time after thereactants are completely charged to give the system time to reachsubstantially complete reaction.

In the use of hydrogen peroxide reactant any excess is decomposed by anyconventional technique. If a solvent reaction medium has been used it isusually possible by proper selection of the solvent to remove thesolvent from the reaction product mixture by distillation. As will bepointed out later in this specification the process of the invention canbe controlled to produce substantially a single reaction product andtherefore normally there will be no need to purify the reaction product.In those cases in which side reaction products have appeared it is usually possible to separate the desired product from the side reactionproducts by conventional techniques in the peroxide art, for example,vacuumdistillation.

a-SUB VINYL ETHERS Ethers of this type needed for use in this processare available commercially. Many methods for preparing these ethers areknown, for example.

(1) Armitage, D. and Wilson, C., J. Am. Chem. Soc., 81 2437 (1959).

' (2) Ansell, M. and Thomas, D., J. Chem. Soc., 1163 (1958).

(3) Trubnikov, I. and Pentin Yu., Zh. Obsch. Khim., 32, 3590 (1962).

(4) Winstein, S. and Ingraham, L., I. Am. Chim. Soc., 77,' 1741 (1955).

(5) Dolliver, M.,' Gresham, T., Kistiakowsky, G., Smith, E., and Vaugh,W., J. Am. Chem. Soc., 60, 440 (1938).

(6) The. commercial base-catalyzed addition of alcohols to acetylenes.

(7) The catalytic cracking of ketals over acid catalysts such ashydrogen chloride, sulfonic acid, and p-toluene sulfonic acid.

ILLUSTRATION OF METHOD 7 Preparation of oz-Sllb cyclic vinyl etherl-methoxy-3,3,5-trimethylcyclohexene Here the ketal was not isolated butconverted directly to the unsaturated ether.

A two-liter round bottom flask was equipped with a two-foothelices-packed column and a variable reflux takeoff head. Attached tothe take-01f head thermometer was the Thermocap relay used to activate aFlexopulse" timer set at a 10 to 1 reflux ratio.

' In a 500 ml. flask was placed 70 g. (0.5 mole) of 3,3,5-trimeth'ylcyclohexanone, 52 g. (0.5 mole) of 2,2-dimethoxypropane, 32 g.(1.0 mole) of methanol, g. of cyclohexane and 0.1 g. ofp-toluenesulfonic acid. The Thermocap relay was set at 52 C., theboiling point of the acetone-methanol-cyclohexane ternary azeotrope.

When the vapor temperature could not be kept at 52 C., the Thermocap wasdisconnected and distillation continued at 10 to 1 reflux ratio. Thebath temperature was raised slowly to C. (temperature of vapor neverrose above 56 C.). When no further distillate came over, the oil bathwas removed, the pot residue allowed to cool and sodium methoxide wasadded to neutralize the catalyst.

The pot residue was then distilled under reduced pressure through a 15inch Vigreux column giving 71.5 g. of1-methoxy-3,3,S-trimethylcyclohexene, boiling at 62 64/C. at 13 mm.pressure, n/ =l.4508. The weight yield was 90.4% but analysis by vaporphase chromatography showed the presence of 9.6% ketone in the ether.The true yield was 82.5%.

The material was used as is in subsequent reactions with no deleteriouseffects.

ILLUSTRATION Preparation of a-sub vinyl ether by vapor phase cracking ofketals A novel method for the preparation of the m-substituted vinylethers cracks ketals in the vapor phase in the presence of solid acidiccatalysts such as alumina, silicaalumina, and the like.

The ketal needed to produce the particular vinyl ether wanted can bemade by the conventional alcohol exchange or ketone exchange reactions.Each of these is illustrated by an embodiment using2,2-dimethoxypropane, a commercially available material, as onereactant.

( M6 OR .5 1412- -Me znon Me- Me 2Me0H Me n J H H Me- Me R-C-OHaRR-CCH2R Me-C-Me Me Me Preparation of 2,2-diisobutoxypropane The alcoholexchange is illustrated:

A two-liter round bottom flask was equipped with a two-foothelices-packed column and a variable reflux take-off head. Attached tothe take-01f head thermometer was the Thermocap relay used to activate aFlexopulse timer set at a to 1 reflux ratio. In the pot was placed 208g. (2.0 moles) of 2,2-dimethoxypropane, 325.6 g. (4.4 moles) of isobutylalcohol, 200 g. of cyclohexane and 0.2 g. of p-toluene sulfonic acid.The flask was surrounded by a 110-120? C. oil bath. The thermocap relaywas set to operate at 54, the boiling-point of the 62% cyclohexane-38%methanol azeotrope. The reaction was continued until the temperature ofthe vapors could not be kept at 54 C. The oil bath was then removed. Thecyclohexane in the distillate was recovered by extracting the methanolwith a water wash. When the pot residue had cooled, sodium methoxide inmethanol (from 0.5 g. of sodium and 25 ml. of methanol) was added toneutralize the acid. The oil bath was then taken to 130 C. anddistillation resumed at 10 to 1 reflux ratio. When no further distillatecame over, the residue was distilled under reduced pressure. After asmall forefraction of cyclohexane and isobutyl alcohol, 293.5 g. (78%)of 2,2-diisobutoxypropane was collected at 91-93 C. at 45 mm. pressure.

Preparation of alkyl isopropenyl ethers This is an example of the solidcatalytic cracking of a ketal to give the corresponding unsaturatedether.

A 25 mm. O.D. Pyrex tube was packed for a length of seven inches withAlcoa Ms spherical catalytic alumina 1 -110. Through the center of thevertical tube was a thermometer with the bulb about A of the length downthe column. The column was electrically heated with tape and insulatedwith glass wool. On the top of the column was a dropping funnel chargedwith 2,2-dimethoxypropane. The cracked vapors passing out the bottom ofthe tube were condensed by a coiled tube condenser through which wascirculated cold water. The receiver was protected with a calciumchloride tube and provision for nitrogen flushing of apparatus and wasimmersed in an ice bath. The column was heated to an internaltemperature of C. and kept between 140 C. and 160 C. (mostly at C.)while about 125 g. of ketal was dropped through the column in two hours.To the condensate was added about 0.1 g. of sodium before it wasdistilled at atmospheric pressure through a two foot helices packedcolumn, 59 g. of methyl isopropenyl ether was collected at 32-33 C. Thiscorresponds to a conversion of 68.3%. In this experiment the residue wasnot recycled.

In the preparation of isoamyl isopropenyl ether, as above, uncrackedketal was recycled four times giving 60% and 62% conversions on thethird and fourth passes through the column.

Isopropyl isopropenyl ether and isobutyl isopropenyl ether were alsomade by the above procedure.

Preparation of alkoxycycloalkenes Cyclic ketals are readilymade by theketone exchange reaction. These readily crack in the vapor phase solidcatalytic cracking reaction to give the corresponding substituted cyclicvinyl ethers. The known vinyl ether: 1- methoxycyclohexene was made. Thefollowing new compounds were made: l-methoxycyclopentene; l-methoxy-3,3,S-trimethylcyclohexene; l-methoxycycloheptene; andl-methoxycyclooctene.

ILLUSTRATION OF ROPP METHOD RESULTS Methyl isopropenyl ether was addedto a cold (0-5) ethereal solution of t-butyl hydroperoxide and acatalytic quantity (one drop) of concentrated. sulfuric acid. Thereaction is exothermic and the temperature was controlled by the rate ofaddition of the vinyl ether and external cooling. The mixture was thenstirred several hours although it is very likely that the reaction isvery fast. The reaction mixture was washed with 10% potassium hydroxideto destroy the catalyst and to remove any excess hydroperoxide. Theethereal solution was then washed with water, dried over sodium sulfateand stripped in vacuo.

The active oxygen assays were consistently greater than theoretical eventhough unreacted hydroperoxide was completely absent from the products.It was at first believed that the fault lay with the assay method. Asample of 2-methoxy-2-t-butylperoxy propane was distilled under reducedpressure through a short column. Although the material distilled over anarrow range, a VPC scan at 80 on a 6 foot diisodecyl phthalate on 60-80WAW810 column showed two sharp bands one at 13.7 min., the other at 40.4min. By careful fractionation, two fractions were separated. Fraction Bdistilled at 36-41 at 4-5 mm.; n 1.3995; active oxygen 10.7% (theory forZ-methoxy- Z-t-butylperoxy propane 9.87%).

Fraction A distilled at 44-46 at 4-5 mm.; u 1.4063; active oxygen 14.2%(theory for 2,2-bis-t-butylperoxy propane 14.5%). That fraction A was2,2-bis-t-butylperoxy propane was established by the synthesis of anauthentic sample from acetone and t-butyl hydroperoxide (its properties;active oxygen 14.3%; 1.4064). The infrared spectrum of fraction A andauthentic 2,2-bis(t-butylperoxy) propane were superimposable. Even whenstoichiometric quantities of methyl isopropenyl ether and tbutylhydroperoxide were used with an acid catalyst, the active oxygen assaywas high.

It was postulated that the methoxy group of Z-methoxy-2-t-butylperoxypropane exchanged ,with t-butyl hydroperoxide in the presence of an acidcatalyst to give 2,2-bis(t-butylperoxy) propane.

CH: CHaO --OOC(CH2)9 (CHOaCOOHZ l C 4 (CHs)aCOO(:3'OOC(CHs)a CHaOH GHQILLUSTRATIONS OF THE PROCESS OF THE INVENTION It was discovered thathydroperoxides add to oc-Sllbvinyl ethers quantitatively in the absenceof acid catalyst. On the other hand non-substituted vinyl ethers reactvery slowly, some not at all, in the absence of an acid catalyst.t-Butyl hydroperoxide quantitatively adds to isopropyl isopropenyl etherto give Z-isopropoxy-Z-t-butylperoxy propane. At identical reactionconditions less than a yield of u-t-butoxy-a-t-butylperoxy ethane wasobtained from t-butyl vinyl ether.

This catalyst-free process possesses several important advantages overthe acid-catalyst process: (a) there is no alkoxy group exchange evenwhen excess hydroperoxide is present, (b) washing of the product isunnecessary, (c) the reaction is less exothermic than the catalyzedreaction, therefore temperature control is simplified and, (d) becauseof (c), a reaction solvent medium is not necessary but may be used.

EXAMPLE 1 2-isopropoxy-2-t-butylperoxy propane To a well-stirredsolution of 11.5 g. (0.115 mole) of isopropyl isopropenyl ether in 50ml. of ether was slowly added 9.1 g. (0.1 mole) of 99% t-butylhydroperoxide. The addition required 40 minutes. There was a slightexotherm and temperature rose to 30. Stirring was continued for 1 hour;then at 3234 (warm water bath) for 1% hours. The ether was removed underreduced pressure leaving 18.5 g. of a colorless oil containing 7.28%active oxygen (theory, 8.41% An infra-red spectrum of the oil was freeof OH absorption but showed as light C=C absorption.

8 EXAMPLES 24 Using the appropriate reactants in the process of Example1 the following were made.

(2) Z-methoxy-2-t-butylperoxy butyric acid, ethyl ester. (3)2-ethoxy-2-t-butylperoxy butyric acid.

A pure butyric acid of Example 3 was not obtained. The product includedsome 2,2-bis(t-butylperoxy)butyric acid.

EXAMPLE 4 2-methyl-2-hydroperoxytetrahydrofuran An ethereal solution ofhydrogen peroxide was prepared by extracting 70% hydrogen peroxide withether and drying the ethereal extracts for 16 hours over sodium sulfate.

To 550 ml. of an ethereal solution containing 46 g. (1.35 mole) ofhydrogen peroxide in a jacketed reactor was added over a minute period60 g. (0.715 mole) of Z-methylene tetrahydrofuran. The temperature wasmaintained at 22-24 during the addition. The mixture was then stirredfor 7 hours at 2832. The reaction mixture was then washed with aqueousammonium sulfate until free of hydrogen peroxide (catalase test). Theethereal solution was then dried over sodium sulfate, filtered andstripped in vacuo. The residue of 2-methyl-2-hydroperoxy-tetrahydrofuran weighed 57.7 g. (68.5% yield) and assayed12.4% active oxygen (theory 13.5% A.O.). An infrared spectrum showed aweak band at 1650 crn. indicative of a small amount of unreactedunsaturated ether in the product.

In a smaller run an 89% yield of the hydroperoxide was obtained and itassayed 86.4% of theoretical active oxygen.

A portion of the product was distilled under reduced pressure; B.P. 4143at 0.6 mm.; n 1.4460; active oxygen 95.6% of theory.

EXAMPLE 5 2-isoamyloxy-2-hydroperoxy propane was prepared in a similarmanner. However, the reaction was much slower.

EXAMPLE 6 Z-methyI-Z-hydroperoxy tetrahydropyran was prepared in asimilar manner.

COMPOUNDS In Table 1 are listed peroxyesters, peroxycarbonates andperoxycarbamates of these three alkoxyhydroperoxides The 011 wasstripped for an additional 20 minutes under i h h i a says d half-liveTABLE 1 Yield, Assay, percent percent 12% C.)

1 2-methyl-2-perbenzoxy tetrehydrofuran 78 99.6 3.2 hours.... 85

2-- 2-methyl-2-peracetoxy tetrahydroiuran.... 36 89. 6 20.0 hours...(85; 3- 2-methyl-2-perpivaloxy tetrahydroiuran 67 95. 3 6.2 hours. (50)4. 2-methy1-2-tetrahydrofurylperoxy N-cyclohexyl earbamate 66 99. 4 1 5.2-methyl-2-tetrehydroiurylperoxy N-methy1cerbamate 100 94. 9 22.8hours-.. 6. 2-methy1-2-tetrahydrofurylperoxy, isopropyl carbonate 62 97.6 3.2 hours.-.. (86) 7 2-methyl-2-perbenzoxy tetrahydropyran 89 96. 010.2 hours..- (50) 8..-... 2-methyl-2-perpivaloxy tetrahydropyran 57 96.3 2.1 hours- (50) 9 2-methyl-2-tetrahydropyrenylperoxy isopropylcarbonate 70 95. 8 10.6 hours-.. (60) 10... 2-ls0amy10xy-2-perbenzoxypropane 100 95.0 7.7 hours-.-- 11 2-isoamyloxy-2-perpivaloxy propane 3499. 0 2.9 hours (50) 12 2-isoamyloxy-Z-propylperoxy, isopropyl carbonate47 94. 3 4.1 hours--. (86) 13 l-methoxy-l-perbenzoxy cyelohexene 46 63.5

I Not stated because this compound did not decom use in the conventionlfir r 1 Not determined because of low assay. p a St 0 der manner waterpump vacuum. The residue weighed 17.3 g. (91.1% yield) and assayed 8.19%active oxygen (97.4% of theory).

COMPOUNDS The dialkoxy peroxides in Table 2 were prepared by adding theunsaturated ether to a-alkoxyhydroperoxide.

1 Not determined because 01 low assay.

9 POLYMERIZATION calculated from styrene polymerization data obtained byconventional dilatometry. The polymerization data are summarized inTable 3.

TABLE 3.-STYRENE POLYMERIZATION Peroxide (III) (OHn)n C O CH!Polymeriza- Polymertion rate at ization convertemp., sion, m./l. n R 0.min. X10

3 Phenyl- 85 2. 91 3 Methyl 85 3. 01 3 t-Butyl- 50 2.24 3 Methylamino 702. 48 3 Isopropoxy 85 3. 01 4 t-Butyl 50 3.28

CH: O CHICH(CH1)CH2CHflO-OO R 23. Phenyl- 85 5. 12 24- t-Butyl- 50 2. 8625 Isopropoxy 85 7. 32 26- 100 8. 62 27- 85 4. 12

l Bis 2,2(2-methyltetrahydrofuryl) peroxide. 2 Bis 2,2(Z-methyltetrahydropyranyl) peroxide.

VINYL CHLORIDE Z-methyl-2-perpivaloxytetrahydrofuran was compared tot-butyl perpivalate as an initiator in vinyl chloride polymerization at50 C. The amount of initiator per 100 g. of monomer required to give 90%conversion to polymer was 0.050 g. of perpivalate and 0.042 g. ofZ-methyl 2-perpivaloxy tetrahydrofuran.

COMPOUNDS IV It is to be understood that the compounds set out instructural Formula IV herein are indeed as broad as so defined. The newprocess herein permits reactions to proceed even though the reactantsare complex compounds as long as substituents do not interfere with theaddition reaction at the vinyl bond.

In addition to species of Formula 1V already disclosed the followingspecies are set out, in their structural form, to illustrate compoundscoming within the definition of L koo-LNH. 0H}

(e) CHQCHlO O CH:- -CH|- -OO-C(CH CHIO O CH;

0 CHr-(B-CH;

COMPOUNDS V The broad statement made with respect to Compounds IV isalso applicable to the compounds set out in structural Formula V.Additional species of this group identified as Compounds V, in theirstructural form, are set out as illustrative of this group.

Thus having described the invention what is claimed is: 1. An etherperoxide having the formula:

R is H, alkyl of 1-3 carbons or cyclohexyl;

R and R are H, methyl or cyclohexyl;

R is alkyl of 1-3 carbons; and

R is alkyl of 1-4 carbons or phenyl.

2. An ether peroxide of claim 1 wherein R is H.

3. An ether peroxide of claim 2 wherein R is H.

4. The peroxide 2-methy1-2-perbenzoxy tetrahydropyran.

5. The peroxide Z-methyl-Z-tetrahydrofurylperoxy N- methyl-carbamate.

6. The peroxide bis-2,2-(Z-methyl-tetrahydrofuryl) peroxide.

7. The peroxide bis-2,2-(Z-methyl-tetrahydropyranyl) peroxide.

References Cited UNITED STATES PATENTS 4/1962 Weissermel et a1. 260347.8

OTHER REFERENCES HENRY R. JILES, Primary Examiner B. I. DENTZ, AssistantExaminer US. Cl. X.R.

